This application claims the priority of German patent 198 37 166.7, filed Aug. 17, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a disk brake having a brake disk and a lining device which interacts with the brake disk and is held on a caliper, the brake disk having a concave brake disk surface on the side of the lining device facing a brake lining surface.
Disk brakes are well suited for a targeted deceleration of a vehicle but, during slow-down braking operations in the low system pressure range, for example, when a vehicle approaches a pedestrian crossing, a traffic light or the like, may cause noises which may have a disturbing effect on pedestrians, among others.
For avoiding a non-uniform wear of brake disks, it is known from German Patent Document DE 43 36 094 A1 to enlarge a brake disk by contouring. In one embodiment, the brake disk therefore is arched in a concave manner. By means of this construction, the described disturbing noises can hardly be avoided.
It is an object of the invention to improve the brake disk and the lining device of a disk brake such that, while the braking effect is good, noise emissions under corresponding operating conditions are at least reduced.
According to the invention, this and other objects have been achieved by a disk brake for a vehicle, comprising: a brake disk having a concave brake disk surface; a lining device supported on a caliper, said lining device having a convex brake lining surface facing said concave brake disk surface of said brake disk.
The principal advantages achieved by the invention are that, as a result of the concavity of the brake disk surface and the convexity of the brake lining surface, a centering of the two surfaces with respect to one another is caused during the braking operation. This results in a functionally appropriate form closure and reduces disturbing noises, for example, during slow-down braking at pedestrian crossings and traffic lights.
A particularly good function is achieved if the concavity of the brake disk surface is determined by a concavity factor equal to or larger than 3, as further described below. If the guiding factor F, as further described below, influencing the form closure is equal to or larger than 1.8, the low-noise interaction of the surfaces is additionally promoted. A further optimization is achieved if the effective brake lining length LW, as further described below, is dimensioned as a function of the medium friction circumference line UM of the brake disk surface and of the number of vibration nodes.
In the cross-sectional view, the concavity of the brake disk surface and the convexity of the brake lining surface is formed by one radius respectively. However, it is also possible to form the concavity and the convexity by an arbitrarily arched curve or two straight lines each extending at an obtuse angle with respect to one another. Finally, it is also contemplated to provide one or several passage ducts between the brake disks, and the wall thickness of the brake disks may vary in the radial direction.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.